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From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Yufen Yu <yuyufen@huawei.com>,
	Christoph Hellwig <hch@infradead.org>,
	Hou Tao <houtao1@huawei.com>
Subject: Re: [PATCH 1/4] block: fix use-after-free on cached last_lookup partition
Date: Thu, 7 May 2020 07:16:26 -0700	[thread overview]
Message-ID: <20200507141626.GA11551@infradead.org> (raw)
In-Reply-To: <20200507085239.1354854-2-ming.lei@redhat.com>

On Thu, May 07, 2020 at 04:52:36PM +0800, Ming Lei wrote:
>  	for (i = 1; i < ptbl->len; i++) {
>  		part = rcu_dereference(ptbl->part[i]);
>  
>  		if (part && sector_in_part(part, sector)) {
> +			if (!hd_struct_try_get(part))
> +				goto exit;

I think this needs the comment that was in blk_account_io_start to
explain the logic.  Also no need for the goto, this can just be a break.

> -	rcu_assign_pointer(ptbl->last_lookup, NULL);
>  	kobject_put(part->holder_dir);
>  	device_del(part_to_dev(part));
>  
> @@ -393,6 +402,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  	p->nr_sects = len;
>  	p->partno = partno;
>  	p->policy = get_disk_ro(disk);
> +	p->disk = disk;

Do we really need this pointer?  Can't we use part_to_disk in the
free path for some reason?

  reply	other threads:[~2020-05-07 14:16 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-07  8:52 [PATCH 0/4] block: fix partition use-after-free and optimization Ming Lei
2020-05-07  8:52 ` [PATCH 1/4] block: fix use-after-free on cached last_lookup partition Ming Lei
2020-05-07 14:16   ` Christoph Hellwig [this message]
2020-05-08  1:54     ` Ming Lei
2020-05-07  8:52 ` [PATCH 2/4] block: only define 'nr_sects_seq' in hd_part for 32bit SMP Ming Lei
2020-05-07 14:16   ` Christoph Hellwig
2020-05-07  8:52 ` [PATCH 3/4] block: re-organize fields of 'struct hd_part' Ming Lei
2020-05-07 14:16   ` Christoph Hellwig
2020-05-07  8:52 ` [PATCH 4/4] block: don't hold part0's refcount in IO path Ming Lei
2020-05-07 14:20   ` Christoph Hellwig
2020-05-08  1:59     ` Ming Lei
  -- strict thread matches above, loose matches on Subject: below --
2020-01-09  6:21 [PATCH 0/4] block: fix partition use-after-free and optimization Ming Lei
2020-01-09  6:21 ` [PATCH 1/4] block: fix use-after-free on cached last_lookup partition Ming Lei
2020-02-21  3:05   ` Yufen Yu
2020-02-21  4:03   ` Bart Van Assche
2020-02-21  7:47     ` Ming Lei

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